Tool for cutting abrasive wheels and other materials



Feb. 26, 1952 D. FINKE 2,587,132

TOOL FOR CUTTING ABRASIVE WHEELS AND OTHER MATERIALS Filed Jan. 29, 1946 Patented Feb. 26, 1952 UNITED STATES PATENT OFFICE This invention relates to tools having diamond points to cut and true abrasive wheels and for related uses to which diamond pointed cutting tools are put. More particularly the invention relates to means for adjustably mounting the holder in which the diamond point of a cutting .tool is rigidly mounted and for resiliently supporting said holder in order that (a) the pressure of the point against the work may be controlled and regulated and (b) that the point of the diamond may be directed opposite the rotation of the'work and (c) to accomplish other purposes and achieve other advantages as hereinafter set forth.

Some of the factors which need to be considered in the use of such tools are: (1) the diameter and width of the abrasive wheel which is to be trued or cut, (2) the grain size of the Wheel, (3) the hardness of the abrasive particles in the wheel, (4) the structure of the wheel, (5) bonding of the Wheel, (6) friction developed, ('7) the pressure of the diamond point against the wheel, and (8) the diamond shape, 1. e. relation of contact to the wheel. Heretofore little attention has been given to the correlation of these factors. Particularly, the pressure factor and the relation of the diamond to the Wheel have not been given the consideration which their importance warrants.

Heretofore the common practice has been to direct the diamond point in the direction of rotation of the wheel to be dressed with the result that the motion of the wheel surface was across the grain of the diamond. According to my invention, the point of the diamond is directed against the direction of rotation of the abrasive wheel with the result that the motion of the wheel surface is substantially with the diamond grain. This is made feasible by the novel structure of my new diamond mounting and tool and by its ability to be adjusted Within microscopic limits for regulating the pressure of the diamond point against the wheel, after the point has been set properly for the out which it is desired to make in truing or dressing the abrasive wheel.

Therefore, one object of my invention is to provide a mounting for the holder of the diamond point of a cutting tool which will provide resilient controlled pressure, in the desired amount, of the point against the wheel which pressure will be automatically maintained.

Another object is to provide, in a tool of the foregoing type, for rotating the diamond without removing the tool from its .fixed location and without need for varying the pressure adjust ment.

Another object of the invention is to provide in a tool of the foregoing type, means readily to adjust the amount of pressure applied by the point against the abrasive wheel.

Another object of the invention is to provide manually operable means in the mountingstructure of a tool of the foregoing type by which the position of the diamond may be varied depending on whether a truing or a dressing is to be done. 7

Many other objects and advantages will become apparent as the invention is described in the accompanying drawing.

In the drawing:

Fig. 1 is a side elevation view of a tool embodying my invention;

Fig. 2 is a longitudinal mid-section view of the invention illustrated in Fig. 1;

Fig. 3 is a plan view of the invention illustrated in Fig. 1;

Fig. 4 is a side elevation view of another form of'the invention;

Fig. 5 is a longitudinal mid-section view of the form of the invention illustrated in Fig. 4;

Fig. 6 is a side elevation view of a third form of the invention;

Fig. '7 is a longitudinal mid-section view of the form of the invention illustrated in Fig. 6;

Fig. 8 is a side elevation view partly in section of a fourth form of the invention;

Fig. 9 is a view of the form of the invention illustrated in Fig. 8 looking in the direction of the arrows along the line 99 of Fig. 8; and I Fig. 10 is a section view taken along line Ill-i0 of Fig. 9.

Referring to the drawings and particularly to the invention as illustrated in Figs. 1-3, an obliquely angulated holder ID has a leg portion l 2 by which the tool is fixed in proper position in relation to the abrasive wheel 14 which is. to be dressed. An arm I6 is formed integrally with the leg portion l2 and extends obliquely to that leg portion. Through the arm 16 is a central bore receiving the cylindrical stem 2!] of a rotary head or diamond holder 22. The head has a flange or skirt 23. The top of the head is recessed for the reception of brazing material 26 in which the diamond point 21 is rigidly and permanently mounted. The recess may be undercut to hold the brazing material. Preferably, the top opening of the recess may be shaped into converging" star-form as by a hammer blow on a pointed five ribbed mandrel. Such form provides an improved and more satisfactory mounting for the diamond point because of. long-side adhesion to the diamond support and setting.

Beneath the head 22 and between it and a conical formation on the arm I6 is an annular cushion of heat resistant rubber 28 such as neoprene against which the head 22 may be pressed, as will presently be described, for the purpose of providing suitable pressure of the point 2'! against the Wheel [4.

From the rear end of the stem 20 extends a screw threaded end 30 of reduced diameter. Threaded upon the end 30 is an annular micrometer adjustment member 32 having an inner conical portion 34 engageable with a complementary conical seat 33 on the bottom side of the arm 16. The adjustment member 32 may be annularly recessed around the bottom of the conical portion 36 to provide for the reception of a thin annular packing member 38 forming a dirt seal. A lock nut 40 is screwed on the end of the extension 30.

From the foregoing it may be understood that by rotating the adjustment member 32, its position axially along the threaded end 30 of the stem 20 can be varied. Such variation in position i. e. different settings, will cause the head 22 to compress the rubber cushion 28 to a greater or less degree. Thus the pressure of the cushion on the head 22 (urging the head upward in Fig. 2) will be greater or less. When the desired pressure is attained, the lock nut 40 may be tightened to maintain that pressure and setting.

It should be noted that adjustment is not provided'for the purpose of locating the position of the diamond point relative to the wheel, after the tool has been secured. The adjustment is to create a predetermined pressure against the diamond holder within the tool that supports it. Thus, I provide a cushion mounting for the diamond point. When the tool is set properly for cutting the desired amount off the wheel, the.

diamond will make the desired cut but while doing so it can accommodate itself to conditions and will allow pointing of the diamond against the direction of rotation of the wheel as hereinafter more fully described.

It will be observed that the shoulder 25 between the cylindrical mid portion 20 and the extension 38 is spaced from the adjustment member 32. It thus is possible for the diamond holder to move axially. Such axial motion is directed against the pressure of the rubber cushion 28. When the diamond point 21 is brought againstthe grinding wheel I4, the amount of pressure which it will exert against the wheel is limited in amount to the degree of compression of the cushion 28 (i. e. by the setting of the adjustment member 32). Any greater pressure, such as may temporarily occur, will simply result in compression of the cushion beyond the degree of compression imparted by the setting of the adjustment member 32. Upon passing of the condition which caused said further compression, the cushion will immediately return the head 22 and diamond point to its previous set position; and the setting of the adjustment member 32. Thus the predetermined pressure of the cushion may persist unaltered through the remainder of the dressing or truing operation. By this means, ex-- cess pressure and excess friction is absorbed, expansion and breakdown of the matrix are avoided, and shock and heat on the diamond are controlled; also fracturing, loosening, broken edges, and loss of diamonds are substantially eliminated; also by reason of ability to rotate the diamond in combination with the cushioning provision, periodical resetting of the diamond is practically eliminated. Thus diamonds could be set in softer matrices, i. e. metals which surround and hold the diamond. It is well understood that overheating of diamonds is sometimes caused before they are actually put into use when they are set in hard matrices, which have high melting points, because excessive heating and cooling set up internal stresses which are destructive.

Therefore gouging and burnishing of the wheel is prevented with the result that there are less pieces of work spoiled than in the case of the conventional tools heretofore used in the art. All

. of these advantages tend. to increase diamond life considerably and to reduce costs.

The provision for pressure adjustment and for cushion of the diamond holder enables the diamon point to be directed in a direction opposite the rotation of the wheel contrary to the usual practice in the art. Experience has shown that diamond points mounted by means of and according to the principles of this invention last many times longer and perform their cutting operations in a much more satisfactory manner than tools for similar purposes heretofore used in the art.

Ability to point thepdiamond opposite the direction of rotation of the wheel causes the diamond to execute a cutting action in a manner similar to a plow. Thus the diamond tends to penetrate under the wheel surface or any loading or glaze. In case there should be unusual conditions or unusual surface pressure or hard spots, the diamond will recede due to excess pressure. As the hard spot or high spot is removed, the pressure carried by the cushion 28 will move the head 22 and point 21 outwardly of the holder. Such outward movement will be limited by the cone 34 coming up against or banking against the conical seat. 36. Thus the diamond holder and point will automatically and ultimately come to a definite stop at the originally set position; but if much stock is to be taken off several passes over the wheel may be necessary. By directing the diamond in the manner indicated and by reason of the cushion provided, a greater out can be made on the wheel than heretofore and the diamond will adjust itself automatically to the proper out without injury to itself or the Wheel.

The foregoing are important advantages because heretofore diamonds did not penetrate under the wheel surface but tended to compress the loading material into the wheel which caused one or more of the following undesirable results; loosening of grit beyond the point of diamond contact, compressed areas, friction, out of roundness, lumpy wheel surface, and burnished surfaces; and the wheel structure broke down unevenly. If these conditions existed, cutting was reduced and overheating of the work resulted from excessive friction with accompanying burn marks and surface cracks causing reduced output and ruined work. Furthermore, the area of cutting surface of the wheel was reduced, causing overloading and strain. All these conditions contributed to requiring more and deeper dressings of the wheel and, further, caused excessive wear on and destruction of the diamond.

Since in the present case the diamond leads with the point, there is a tendency to reduce shock because of the small contact area; concomitantly frictionand heat are likewise minimized or nullified. Because the point opposes the direction of wheel rotation, the cut is made in the direction of the strongest diamond structure, namely, with the grain; also the strain on the diamond is by pressure towards its setting and assures not in *a dlrec'tion tending to pull it from its settlngasin present practice. In present practice frictional heating causes expansion of the tool and matrix, which condition tends to loosen the diamond and to allow it to be more easily pulled from its matrix.

By reason of the locking of the adjustment of member'32 by the locknu't 40, it is possible 'with-, out *changing the pressure adjustment of the cushion 28 to rotate the diamond holder or head 22 for the purpose of exposing a new point on the diamond. Such rotation is possible because the cone 34 can slide on conical seat 36 and the frictional resistance of cushion '28 is small so as not to retardrotation of the head orholder 22.

Theability to rotate the diamond in combina: tion with the direction in which the diamond is pointedresults in the diamond beingalways in good condition and of definite shape because there 'is a natural shaping and coning.

Notably the adjustment is to regulate the pressure of the diamond point against the wheel rather than to adjust the over-all position of the diamond point with relation to the wheel. Suchover-all adjustment is made by other means conventionally employed in the art.

Because of the minuteness of the dimensions involved in adjusting the position'of the diamond point relative to the wheel i. e. thousandths of an inch, a small variation in the position of the dia- ;m'ond, brought about by a small change in the angular-position of the axis of the holder will result in either the point being directed against the wheel or the side of the diamond adjacent the point being in contact with the wheel. These difierentc'onditions are obtained during truing and dressing.

In order to vary albeit within small limits, the angular position of the axis of the diamond holder, a slot 50 is provided between the armlB and the leg l2, the sides and ends of which slot may be filled with a resilient cushioning material 52. Aligned with the slot is a screw threaded bore, directed into the top of the arm is for receiving an adjustment bolt '54, having a bevelled end 56 adapted to seat against conical end'walls of the bore. For rotating the adjustment bolt 54 a lever 58 may be affixed upon the outer end of the bolt. As shown in Figure 3, the lever 58 is in a mid position. When moved approximately 90 clockwise, the adjustment bolt 54 will enter further into the bore causing a tilting of the arm IS with respect to the leg I2 some thousandths of an inch, the tilting being permitted by the inherent resilience of the material of which the arm [6 and the leg I! are made. Upon movement of the lever 58 approximately 90 incounterclockwise position from that shown in Figure 3, the bolt 54 will tend to withdraw from the bore whereupon by virtue of the inherent resilience or the material of which the arm [6 and the leg [12 are made, the arm It to tilt downwardly (in Fig. 2) toward the leg l2l Thus when the lever '58 is turned to one side from the mid position in Figure 3, the diamond will be in position for dressing an abrasive wheel by a cutting action, as above described; and when the lever 58 is moved to the other side from the position shown in Figure 3, the diamond is located in position for trui'ng the abrasive wheel by an action in the nature of a honing action, it being understood that in the latter position instead of the point being directed against the direction of rotation, the. "side surface of the diamond adjacent the point of the diamond will be in contact with the wheel. From the foregoing, those mmmar with the art will understand the ru'nctio'ning and operation of the invention notwithstanding the difficulty of illustrating in a drawing the movements of the diamond point during the various adjustments on account of the extremely small dimensions involved in such adjustments.

In order that the diamond point maybe rotated automatically when there is a turning of the lever 58 between dressing and truing, the member 58 may be made of springy metal and provided with a curved or involute arm 59 whose outer periphery engages frictionally with the ser- -rated periphery of the skirt 23. On turning the head 22 by reason of the friction between it and its associated parts.

In the course of use of the tool the diamond point eventually wears down. To indicate when the'point has been worn to a condition where it requires resetting or replacement, a wear ring or rib 29 is provided on the head 22 between the brazing 26 and skirt 23. The ring, being adjacent the diamond, will become worn away by the re-- moved abrasive particles flying from the wheel when the diamond has become worn to the practical limit of its usefulness.

In the form of the invention illustrated in Figures 4 and 5, a cylindrical holder'fiil has a cylindrical passage which is of larger section in its upper end 62, than in its lower end 64. Within the upper end is a cylindrical head 66 recessed in its upper end for the reception of brazing material in which is permanently secured a diamond point ill. The top end of the head 65 has a flange or skirt 6? flaring outwardly and downwardly, forming a concave annular recess beneath the head. The top surface of the holder 60 is preferably conically recessed as at 6 i. Thus a recess, larger in its inner dimension than in its outer, is provided for the reception of a resilient annular cushion 12 of rubber or equivalent material. Cylindrical rod 18 which is screw threaded at its bottom or protrudin end engages with complementary screw threads on the interior surface of the member-50. The shank of the rod 13 being, of course, of less diameter than the screw threads. Upon the lower protruding end of the rod is a head with a diametrical slot 35 on its bottom end for turning by means of a screw driver or like tool to desired pressure setting, which may be indicated by graduations marked on the periphery.

Beneath the member 65 is a resilient pressure adjustment cushion Id of disc shape; and between that cushion and the bottom of the upper bore 52 in the holder is a pressure pad 16 preferably of metal.

Extending transversely through the above described assembly, is a pin 82 having a relieved side surface 84 and a lever S6 attached to an extending end of the pin. The lever enables rotation of the pin to change the location of the relieved portion from that shown to another posi-' adjusted by manipulation of the graduated head 89 to proper pressure. As the head 89 is rotated the pad I9 can move up to compress the cushion I4 and thus increase the pressure upon the holder 89. The holder 69 can recede (move downwardly in Fig. 5) such as when the point I9 hits a hard or a high spot, due to the space provided between the relieved or flat portion of the pin 82 and the top of the slot through which the pin passes. Such recession, however, will not take place until the predetermined pressure of the cushion is overcome; and then the recession is cushioned by the further compression of the cushion I4. The dressing is accomplished by the tool when the parts are in the position illustrated. Truing is accomplished by rotating the adjustment lever or head 86 189 in which case the flat side 84 will permit the holder member 69 to move a small fraction closer to the wheel.

Referring to the form of Figures 6 and '7, the holder comprises a cylindrical member 99 centrally bored for the reception of a stem 92 having a flanged head 93 with a recess for brazing material 94 to hold the diamond point 95. The flanged head 93 is of somewhat similar shape to the flanged head 61 of Figures 4 and 5. The upper end of the holder 99 is screw threaded and has mounted thereon an internally screw threaded pressure regulating sleeve 95 with a concave upper surface to provide an annular recess for a resilient cushion 91 of rubber or the like, by means of which the pressure exerted against the head 93 may be varied.

The lower end 98 of stem 92 is of reduced section having a screw threaded end portion. Mounted on the screw threaded end is an internally threaded adjustment collar 99 having a lever 99a extending radially therefrom. The collar 99 lies within an enlarged circular bore in the lower end of the main holder 99 and seats upon the shoulder between that enlarged bore and the smaller bore within which the rod-like extension 98 is located. A look nut 9| may be provided to fix the position of adjustment of the adjustable washer 99.

From the foregoing it may be observed that in Figures 6 and 7 the position of the diamond point and its holder 92 may be adjusted relative to the main body of the holder 99 and that adjustment may be fixed by manipulating the lock nut 9|. Such adjustment may be made by turning by hand the flanged head 93 while holding stationary the holder 99. The holding of the holder 99 will at the same time hold stationary the collar 99, because the lever 99a extends through the slot 99s and is held from rotation thereby. However, the lever'99a can move axially, when required to do so by receding of the diamond point.

The amount of pressure exerted by the cushion 91 may be adjusted to a predetermined degree by rotation of the collar 99.

Thus after the lock nut 9| is tightened the diamond point may not move closer to the work or the abrasive wheel because the adjustment collar 99 prevents such movement beyond the adjusted position; but the point may move away from the wheel against the cushion 9?. The cushion 9'I affords a uniform pressure of predetermined amount according to the requirements of the particular job, as in the previously described forms of the invention.

Referring now to the form in Figures 8, 9, and 10, the holder I99 (of somewhat similar shape and form to the holder I9) has a leg H2 and an arm III; with a slot at their joint. There is provision for varying the angularwrelation between the leg and the arm by means'of a bolt I54 which passes through a bore in the leg I I2 and threads into a continuation of that bore in the arm HE. A lever I58 is conveniently provided upon end or head of the bolt I54 for the purpose of manipulating the bolt. It will be observed that the bolt I54 works transversely relative to the slot so that upon turning the bolt the slot is narrowed causing the angle between the leg H2 and arm II6 to be lessened. Upon turning the bolt to withdraw it from the bore (unscrewing) the inherent elasticity of the material of which the holder I99 is made will'cause the leg H2 and the arm H9 to resume their original positions and their .originally angular relationship.

The diamond point 21, as in the previous'forms is mounted in brazing material in a recess in the rotary diamond head I22. Preferably the recess is formed as described in Figures 1-3. This head I22 is recessed on its under surface for the reception of a resilient annular cushion I28. Extending rearwardly from the head I22 intoa bore in the arm I I9 is a stem I29 having a screw threaded end portion upon which is mounted an internally threaded adjustment member I32 in the form of an internally threaded disc. The position of adjustment of the member I32 on the rod I29 may be fixed by a lock nut I49.

The holder II9 may be formed with a bearing collar on its top surface around the bore through which the stem I29 passes. The collar may be cut diametrically, and the half I I9 thereof nearest the leg H2 may be cut so that it becomes a free and se arate element which is held against the stem I29 by the cushion I28. The bearing is thus firm at all times preventing play or tilting, by reason of the rigid half II9 of the bearing fixing the location of the stem and the resilient half firmly holding the'stem thru the pressure continuously exerted by the cushion I28. Because the bearin II8, II 9 extends from the holder H9 additional bearing surface is provided.

The principle of operation and the functioning of the form illustrated in Figures 8 and 9 may be readily understood from the description of the previous forms and particularly from the description of Figures 1-3.

It will be understood that the wear ring and the star form of matrix may be and preferably are employed in each of the forms of the invention even though for the sake of brevity the description or illustration may not be repeated in each instance.

From the foregoing it may be observed that I have provided a novel structure for holding the diamond point of cutting tools and for permitting adjustment of the pressure of the diamond point against the work whereby the point may be directed in a direction opposite the rotation of the wheel. Furthermore the diamond point may be readily rotated so as to wear evenly and so as to present a different side of the point to the work as may be desirable. It may also be observed from the foregoing that in each of the forms of the invention described the pressure of the diamond point against the work may be varied to suit the circumstances and conditions of the work to be done. It is important to distinguish this adjustment pressure from the main adjustment of the tool to the work. Many modifications within the scope of my invention will occur to those skilled in the art.

Therefore I do not limit my invention to the specific embodiments described and illustrated.

What I claim is:

1. A tool for dressing abrasive wheels comprising a holder, a head mounted on said holder and recessively movable Within said holder, a diamond point permanently mounted in said head, resilient means urging said point constantly in the direction it points, and means engaging with said holder to adjust the direction of said point without moving said holder, said holder having a slot in the central portion thereof and being made of springy metal, and said means for adjusting the direction of the diamond point comprising a screw bolt having a tapered end to widen said slot and thereby to vary the angular relation of the parts of the holder to each other.

2. A tool for dressing abrasive wheels comprising a holder, a head mounted on said holder and having a stem extending through said holder, a diamond point mounted in said head, a semicylindrical bearing member integral with said holder for said stem, a semi-cylindrical floating bearing member engaging said stem oppositely from said integral bearing, and a resilient annular member embracing said bearing members and urging said point in the direction it points.

3. A tool for dressing abrasive wheels comprising a holder having a bore, a head having a stem rotatably mounted in said bore, a diamond point 1 a resilient member embracing said bearing mem- 3 bers to hold said floating member against the stem, and concomitantly to exert a pressure on said head in the direction it points.

4. A tool for dressing abrasive wheels comprising a holder, a head mounted on said holder and recessively movable within said holder, a diamond point permanently mounted in said head, resilient means urging said point constantly in the direction it points, and means engaging with said holder to adjust the direction of said point Without moving said holder, said holder having a slot in the central portion there of, and said means for adjustin the direction of the diamond point comprising a screw bolt for narrowing the width of said slot and thereby to vary the angular relation of the parts of the holder to each other.

DANIEL L. FINKE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,033,749 Strong July 23, 1912 1,191,746 Thomson July 18, 1916 1,496,145 Brown June 3, 1924 2,204,855 Healy June 18, 1940 2,345,840 Strong Apr. 4, 1944 2,400,368 Palmer May 14, 1946 FOREIGN PATENTS Number Country Date 15,664 Great Britain Oct. 31, 1888 24,653 Germany Nov. 8, 1883 417,451 Great Britain Sept. 27, 1934 

